Longest text without a repeat

Problem

A form checker reads a word of lowercase letters. Print the length of the longest piece of it in which no letter appears twice.

Example 1

Input

abcabcbb

Output

The piece "abc" has length 3, and no longer piece has all different letters.

Example 2

Input

pwwkew

Output

The piece "wke" has length 3.

Try the problem first. Open one hint at a time.

Hint 1

Keep the letters of the current piece in a set. When the new letter is already in it, drop letters from the left.

Hint 2

Or store the last position of each letter and jump left past it.

Write your Python code, run it on the examples and submit it to hidden tests.